1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
/* mpz_div_2exp -- Divide a bignum by 2**CNT
Copyright (C) 1991 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
The GNU MP Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the GNU MP Library; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "gmp.h"
#include "gmp-impl.h"
void
#ifdef __STDC__
mpz_div_2exp (MP_INT *w, const MP_INT *u, unsigned long int cnt)
#else
mpz_div_2exp (w, u, cnt)
MP_INT *w;
const MP_INT *u;
unsigned long int cnt;
#endif
{
mp_size usize = u->size;
mp_size wsize;
mp_size abs_usize = ABS (usize);
mp_size limb_cnt;
limb_cnt = cnt / BITS_PER_MP_LIMB;
wsize = abs_usize - limb_cnt;
if (wsize <= 0)
wsize = 0;
else
{
if (w->alloc < wsize)
_mpz_realloc (w, wsize);
wsize = mpn_rshift (w->d, u->d + limb_cnt, abs_usize - limb_cnt,
cnt % BITS_PER_MP_LIMB);
}
w->size = (usize >= 0) ? wsize : -wsize;
}
|
